1. Field
This application pertains to archery bow accessories, and is directed to pin sights that can be attached to the riser of an archery bow. It is more particularly directed to a fine adjustment mechanism for such pin sights.
2. State of the Art
Pin sights are in extensive use by archery hunters. Several versions have evolved over the years, in response to the changing demands of the marketplace. A principal driving force for pin sight development has been the advancing technology of the archery bows, with which those sights are used.
A traditional fixed-pin sight usually has 3 to 5 pins, which can be individually set for a particular known distance (yardage). The top pin establishes a selected yardage distance, and progressively lower pins establish correspondingly longer distances. Once set, the pins are tightened and remain “fixed” in position during use. Setting up and adjusting a fixed-pin sight is relatively straight forward, but requires some trial and error testing. Bow hunters typically set their fixed-pins for easy-to-remember distances, usually in 5 or 10 yard increments. Once the pins are set, accurately shooting to known distances is readily accomplished. For example, in preparation for launching an arrow at a target 30 yards distant, an archer simply places the pre-set 30-yard pin on the intended target. The sight inherently compensates for the arrow's normal trajectory at that distance. Targets located at unknown distances present a greater challenge. The archer must estimate the distance, and chose the sight pin most appropriate for that distance, making suitable adjustments to account for any difference between the estimated actual distance and the pin's distance setting. A common three pin setup positions individual pins for 20, 30 and 40 yards. A fixed-pin shooter must learn to compensate as necessary for intermediate distances for which no pin is set. If a target is 25 yards away, the 20 yard pin will shoot a bit too low and the 30 yard pin a bit too high. Accordingly, fixed-pin shooters must learn the technique of “gap shooting;” that is, to hold on the target somewhere between the two pins.
Movable sight pins avoid the need for “gap shooting.” A moveable pin sight usually has a single pin, which is adjusted before each shot. Moveable pin sights rely upon a system of brackets, levers, or worm gears to smoothly slide the entire sight housing (“pin guard”) up and down. The pin can thus be adjusted for any distance within a range in seconds. At the rear of the sight bracket, a small adjustable pointer, linked to the pin, indicates the yardage along a graduated scale (or a series of handmade marks). Each mark represents a known yardage, so the moveable pin sight can be adjusted to any distance by moving the pointer. It is feasible to mark a pin position corresponding to every incremental yard within the distance range of interest. As a practical matter, however, moveable pin scale markings are calibrated at 5 or 10 yard increments. A typical moveable pin sight might be setup with scale marks corresponding to every 5 yards within a 40 yard range, for example 20 to 60 yards. If a target is 27 yards away, the pointer can be set between the 25 and 30 yard scale marks. This system allows yardages to be carefully adjusted on a scale, before the bow string is drawn. In other words, the pin can be placed on the target without further gap adjustment.
Some pin sights provide for “gang adjustment.” That feature provides for movement of a group of pins simultaneously. In a typical such arrangement, loosening a screw permits sliding a dovetail bar up or down in a groove. The entire sight housing and all its associated pins are thereby raised or lowered in elevation. Similarly, a separate fastener allows the entire sight housing and associated pins to be moved horizontally, thereby effecting a “windage” adjustment. These capabilities make initial setup and sighting-in easier and provide a greater range of available settings.
Generally, gang adjustments are made by loosening a screw and then sliding the sight housing to a new position. Some such sights incorporate a micro-adjust feature which allows gang windage and elevation adjustments to be made by turning an adjustment knob (usually attached to a simple gear that drives the motion of the housing). These “Micro Adjust” sights are very precise and easy to work with, but they are typically quite expensive.
As compound bows have evolved to deliver faster arrow speeds and flatter trajectories, the space between sight pins (pin gaps) has tended to become smaller. For example, a bow that shoots an arrow faster than 300 feet per second may be paired with a pin sight in which the 20 yard pin is virtually stacked right on top of the 30 yard pin. Close vertical pin spacing is usually accomplished through the use of multiple pin-tracks and/or angled pins such that one pin can be literally set on the edge of another. Sights designed with this feature are said to have “zero pin gap” capability.
A previously known pin sight arrangement improved upon by this invention is embodied in the “Optima Professional” sights disclosed in the 1994 Browning Archery Catalog, the description of which is incorporated by this reference as a portion of this disclosure. That sight mounts individual pins in respective individual pin holders. A plurality of such pin holders are positioned in stacked column arrangement within parallel channels such that the vertical position of each pin is individually adjustable by means of a lead screw (elevation tracking screw). The pins may thus be individually positioned in close proximity within the pin guard of the sight. Because the spacing of adjacent pins within a channel can only be reduced to a lower limit dependent upon the dimensions of the pin holders, (which remain within the channels), these spacings are larger than what is currently regarded as “zero pin gap.” To achieve closer spacings requires expedients, such as bent pins, that are undesirable from a manufacturing standpoint, and distracting to an archer.